In the sport of rowing, there are rigid members attached to the side of a hull to hold a cylindrical pin at the appropriate distance from the boat. These are called riggers. An oar lock holds an oar and rotates around a pin. The main object of a rigger is to support the force generated by the user. An important feature in a rigger is its adjustability. Adjustability is important so that the rigging measurements may be customized to the user for optimal performance. One of the measurements many users desire to change is pitch. Pitch can be measured in two common ways, stern and lateral pitch. Stern pitch is the angle of the pin relative to the lengthwise axis of the boat. Lateral pitch is measured relative to the axis perpendicular to the lengthwise axis.
There are many classes and types of riggers that generally fall into two categories. The first class is fixed pitch riggers. These riggers have a pin bolted into a slot, with a fixed pitch. The pitch on the pin with these riggers is usually made to be zero (0) degrees both stern and lateral, which causes the pin to be vertical. The pitch may be adjusted on these riggers. However, it is a very difficult process which involves carefully bending the pin to the desired angle. This process is also potentially damaging to the rigger and the boat as it relies on plastic deformation of the rigger.
The second class of riggers is those which support the pin from a single bracket member which attaches both to the top and bottom of the cylindrical pin.
Some of these riggers allow the adjustment of pitch, some do not. Most riggers allowing pin pitch to be adjusted use a bracket to support the pin from both the top and bottom. There are a wide range of shapes the bracket could potentially take, but all of these have in common two holes spaced apart to accommodate a pin. With this type of rigger allowing adjustable pitch, the bracket is usually in a semi circular or semi-spherical shape and the stern and lateral pitch may be adjusted by loosening a bolt. The stern pitch is adjusted by sliding the bolt along a slot in the bracket to change the stern pitch angle. Lateral pitch is adjusted by rotating the bracket about the bolt. This is made possible by the spherical shape of the bracket at the point where the bracket meets the rigid members extending from the boat. The bolt is tightened once the desired pitch is found. One problem with this system is that over time, the bracket will slide and the pitch angle will change. Additionally, when re-tightening the bolt to secure the pitch, the bracket usually moves with the torque generated by the rotation of the bolt. The other problem is that adjustment of this rigger requires a relatively high amount of skill, and ultimately is a waste of time for an athlete or coach.
Others of this second class of riggers do not allow any adjustment of pitch through simple methods as the bracket is attached to the rigger at a fixed pitch. One of the methods used for adjusting lateral pitch on these riggers involves bending the rigger so that it deforms and is at the desired pitch. In many cases, it is desired that the pitch be adjustable, and few are willing to bend the rigger on their boat for fear of causing permanent damage.
There are two basic mounting systems for riggers including side mount and wing mount. Side mount riggers mount to the side of the hull, and wing mount riggers mount to the gunwale. Further there are two disciplines in the sport of rowing, sweep rowing uses one oar per seat, sculling uses two oars per seat. A sculling wing rigger is one piece holding two pins, one on each side of the boat. A sculling side mount system uses two individual riggers each with one pin mounting to opposite sides of the boat.
U.S. Pat. No. 6,183,325 to Purser discloses that some oarlocks are designed to incorporate bushings or inserts to adjust for pitch and pin diameter. The oarlock inserts cited here only adjust pitch relative to the pin, and not the actual pitch of the pin itself, thus making it impossible to use these inserts to adjust outboard pitch without changing stern pitch. This limitation further makes it impossible to both have the total oarlock pitch to change throughout the stroke cycle and to make the actual total change be adjustable and user selectable.
WO 91/08945 A1 to Carter et al. discloses a method of adjusting pitch that uses a cam system to adjust the oarlock face. Although the structure of this invention is different than the bushing system mentioned in the Purser patent, it is irrelevant for the same reason that the adjustment is not directed to the pin, it is directed to the oarlock. Thus a change in oarlock pitch will result in an equivalent change in both total outboard and total stern pitch. Thus, it is impossible with the Carter patent to both have total pitch change throughout the stroke cycle, and to adjust the total amount of change there is throughout the stroke cycle.